1. Field of Invention
The present invention relates generally to laser heterodyne interferometers, and more particularly to laser heterodyne interferometers used to produce an audible output or digital representation of an audible output representative of the physical structure formed in the helical groove of a cylinder recording, such as an Edison type wax cylinder or a 33, 45 or 78 RPM long play record.
2. Description of Prior Art
Prior to the advent of magnetic tape and digital technology for storage of sound recordings on a medium, sounds were recorded by carving a helical groove in a material, wherein the groove includes undulating vertical or horizontal “peaks” and “valleys” that modulate the frequency of the sounds they represent. To playback the sounds recorded in the 20 groove, a mechanical stylus is positioned in the groove and the groove is rotated at a predetermined speed, thereby causing the mechanical stylus to traverse the “peaks” and “valleys” at an equal speed. The movement of the stylus within the groove is then transferred to a diaphragm that then vibrates at frequencies equal to the modulations. The pressure created through vibration of the diaphragm creates sound waves varying in pitch and tone with the frequency of the vibrations. The sound waves may then be amplified and output through a speaker.
As electronic technology advanced, the vibrating diaphragm was replaced with a stylus that transferred the modulations in the groove to a Piezo electric element that converted the mechanical energy (pressure) into electrical energy (a voltage proportional to the pressure). The electrical signal could then be conditioned, amplified, and sent through a transducer (for converting the electric energy into acoustic energy) for playback through a speaker.
While the prior art technology for playing back the sounds recorded on cylinders is well accepted, the wear and tear on the recording medium as a consequence of the repeated physical contact between the groove and stylus degrades the quality of the audio signal. It is not uncommon, therefore, for a LP record to playback “pops” and other forms of noise due to the breakdown of the “peaks” and “valleys” carved into the groove. In addition, with the early cylinder recordings that were the prevalent form of recordings from around 1895 until around 1929, the medium in which the groove was cut was made of a wax type substance. The repeated friction between the stylus and the wax breaks down the wax and degrades the quality of the recording. With many of these wax cylinder recordings forming an important part of history, the need exists for a device that can playback the sounds recorded on these cylinders without decaying or further degrading the quality of the sound.
3. Objects and Advantages
It is therefore a principal object and advantage of the present invention to provide a system and device that can play back audibly or digitally copy sounds recorded on a cylinder or grooved medium without degrading the medium on which the recording is stored.
It is a further object and advantage of the present invention to provide a system and device for frictionlessly playing back audibly or digitally copying a sound recorded in a groove formed in a cylinder or other grooved medium.
Other objects and advantages of the present invention will in part be obvious, and in part appear hereinafter.